Vitamin B12

What is vitamin B12?

Vitamin B12 belongs to the B group of vitamins. It is also known as cobalamin.

Why do I need vitamin B12?

Vitamin B12 is the energy vitamin, as it plays a key role in energy production and, in partnership with vitamin B9 (folate), it helps the body form healthy red blood cells.

Vitamin B12 also plays a part in DNA synthesis and optimal function of the nervous system. It's involved in the development of myelin, the substance which protects nerve endings and allows them to send impulses to the brain and other parts of the body.

Vitamin B12 is essential for cardiovascular health, as it works with other B vitamins to help regulate homocysteine levels in the blood. Elevated levels of homocysteine in the blood are associated with an increased risk of conditions such as coronary heart disease, atherosclerosis and strokes.

How much vitamin B12 do I need?

The recommendation for a healthy adult is 0.0015mg or 1.5mcg per day.

What happens if I don't have enough vitamin B12?

Vitamin B12 deficiency can occur as a result of an unbalanced diet, prolonged use of certain medication or malapsortion. A deficiency in B12 is commonly linked with pernicious anaemia, an autoimmune condition where the stomach cells are unable to produce a protein called intrinsic factor, which is required for the absorption of B12.

Vitamin B12 deficiency may also impair the body's ability to produce red blood cells, leading to a condition known as megaloblastic anaemia. Some medication used to relieve indigestion, such as proton pump inhibitors, can upset the balance of B12, as they are designed to reduce the production of stomach acid, and this is needed for the absorption of B12.

As the principal sources of vitamin B12 are animal foods, people who follow a vegan diet may be at risk of a deficiency. People over the age of 50 often find it harder to absorb vitamin B12 from their diet. Symptoms of vitamin B12 deficiency include feelings of apathy and fatigue, depression and irritability, poor memory, loss of motivation and muscle weakness.

Where is vitamin B12 found?

The following are good food sources of vitamin B12:

animal sources of food, such as meat, fish, dairy or eggs.

some fortified foods, such as yeast extract or breakfast cereals.

What are the effects of cooking on vitamin B12?

All vitamins are sensitive to heat, and B vitamins are water soluble, which makes them vulnerable to cooking methods such as boiling or stewing, although the benefit of the vitamin can still be found in the juice or the gravy, if this is eaten as part of the dish. Grilling or frying meat can result in up to 20% loss of vitamin B 12.

Do I need to take vitamin B12 supplement?

Healthy adults who include meat, fish and dairy in their diets should not require a supplement to their diet. Vegans may need to consider fortified foods to ensure optimum B12 levels. If you're concerned about your B12 levels, consult your GP, as a simple blood test can easily identify any problem. If you do decide to take a vitamin B12 supplement, the Department of Health recommends that you do not exceed 2mg per day.

What are the side effects and safety precautions of taking a vitamin B12 supplement?

Moderate vitamin B12 supplementation is deemed likely to be safe for most people.

What happens if I take too much vitamin B12?

There is no conclusive evidence to identify the effects of prolonged high doses of vitamin B 12, however it is advisable to remain within recommended limits.

Do vitamin B12 supplements have any drug interactions?

Vitamin B12 may interact with certain medication for conditions such as stomach or intestinal disorders or hypertension. Consult your GP if you have any concerns.

Vitamin A: Vitamin A can be found in carrots and green, leafy vegetables.

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